1. Field of the Invention
The present invention relates to ribbon cartridges for use in impact type printers such as line printers, typewriters and wire-dot printers and more particularly to a ribbon drive assembly disposed within the cartridge and operative to drive the endless ribbon stored in the cartridge.
2. Prior Art
An impact type printer, such as a typewriter or a wire-dot printer, typically uses a ribbon cartridge storing therein an inked ribbon which is impregnated with ink. Typically, the supply of ink with which the ribbon is impregnated will be depleted long before the ribbon wears out. As the ribbon's supply of ink becomes depleted, print quality becomes increasingly lighter. The print quality finally becomes so light as to be unacceptable, and the ribbon cartridge must be discarded.
A variety of re-inking assemblies have been proposed to re-ink the ribbon to thereby derive further use from the ribbon cartridge. A typical prior art re-inking assembly is mounted in the housing of the ribbon cartridge. The re-inking assembly has a re-inking roller which is formed from a porous material saturated with ink. A transfer roller is mounted for rotation tangentially to the re-inking roller. A ink ribbon drive assembly drives and advances an endless loop ribbon so that the ribbon is brought into contact with a portion of the transfer roller as it is advanced along its path. Ink is transferred from the re-inking roller to the transfer roller and then to the ribbon so that the ribbon is continuously re-inked.
In a typical prior art ink ribbon cartridge, the ink ribbon drive assembly is mounted within the housing of the ink ribbon cartridge and has drive gear meshing with an idler gear. The drive gear and idler gear sandwich the ink ribbon therebetween and engage successive portions of the ribbon to move the ribbon along an endless path of travel and past a printing location located outside the housing where the ribbon is engaged by a printing mechanism. As the internal ink ribbon drive assembly advances the ink ribbon, the ink ribbon is fanfolded or "stuffed" into an ink ribbon storage area inside the cartridge housing.
In one prior art, the ink cartridge housing has a top cover to allow the operator to readily access the inked ribbon, a re-inking assembly, and an ink ribbon drive assembly mounted in the ink cartridge housing. A drive gear is mounted on a bracket which is in turn removably mounted within the ink cartridge housing to facilitate maintenance of the inked ribbon, the re-inking assembly and the ink ribbon drive assembly.
The ink ribbon cartridge is designed so that the bracket of the drive gear is somewhat retained between the top cover and the cartridge housing when the top cover is attached to the cartridge housing. Such a design results in various difficulties in the maintenance of the internal assemblies, such as replacement of the inked ribbon or other parts. For example, once the top cover is opened, it is difficult to close the top cover with the drive gear bracket in place. Sometimes, the drive gear bracket is lost during the maintenance work.